A dividing wall made from at least one first wall material for delimitation of a patient positioning region from an antenna structure of a magnetic resonance tomography apparatus has at least one region at which a specific sub-structure of the antenna structure is located on the side of the dividing wall facing away from the patient positioning region, at which the dividing wall has a wall part made from a second wall material with a dielectric constant that is lower than the dielectric constant of the first wall material.